title: Headspace solid-phase microextraction-gas chromatography-mass spectrometry characterization of propolis volatile compounds.
abstract: In this study, a novel and efficient method based on headspace solid-phase microextraction (HS-SPME), followed by gas chromatography-mass spectrometry (GC-MS), was developed for the analysis of propolis volatile compounds. The HS-SPME procedure, whose experimental parameters were properly optimized, was carried out using a 100 μm polydimethylsiloxane (PDMS) fiber. The GC-MS analyses were performed on a HP-5 MS cross-linked 5% diphenyl-95% dimethyl polysiloxane capillary column (30 m × 0.25 mm I.D., 1.00 μm film thickness), under programmed-temperature elution. Ninety-nine constituents were identified using this technique in the samples of raw propolis collected from different Italian regions. The main compounds detected include benzoic acid (0.87-30.13%) and its esters, such as benzyl benzoate (0.16-13.05%), benzyl salicylate (0.34-1.90%) and benzyl cinnamate (0.34-3.20%). Vanillin was detected in most of the samples analyzed in this study (0.07-5.44%). Another relevant class of volatile constituents is represented by sesquiterpene hydrocarbons, such as δ-cadinene (1.29-13.31%), γ-cadinene (1.36-8.85%) and α-muurolene (0.78-6.59%), and oxygenated sesquiterpenes, such as β-eudesmol (2.33-12.83%), T-cadinol (2.73-9.95%) and α-cadinol (4.84-9.74%). Regarding monoterpene hydrocarbons, they were found to be present at low level in the samples analyzed in this study, with the exception of one sample from Southern Italy, where α-pinene was the most abundant constituent (13.19%). The results obtained by HS-SPME-GC-MS were also compared with those of hydrodistillation (HD) coupled with GC-MS. The HS-SPME-GC-MS method developed in this study allowed us to determine the chemical fingerprint of propolis volatile constituents, thus providing a new and reliable tool for the complete characterization of this biologically active apiary product.
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia, Via G. Campi 183, 41125 Modena, Italy. federica.pellati@unimore.it
authors.forename: Federica
authors.initials: F
authors.lastname: Pellati
authors.forename: Francesco Pio
authors.initials: FP
authors.lastname: Prencipe
authors.forename: Stefania
authors.initials: S
authors.lastname: Benvenuti
mesh_terms: D004129:Dimethylpolysiloxanes / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D007558:Italy; D011429:Propolis / Q000737:chemistry*; D052617:Solid Phase Microextraction / Q000379:methods*; D055549:Volatile Organic Compounds / Q000737:chemistry*
chemical_list: D004129:Dimethylpolysiloxanes; D055549:Volatile Organic Compounds; D011429:Propolis
keywords: DVB-CAR-PDMS; Gas chromatography; HD; HS; LRI; Mass spectrometry; PDMS; Propolis; Solid-phase microextraction; Volatile compounds; divinylbenzene-carboxen-polydimethylsiloxane; headspace; hydrodistillation; linear retention index; polydimethylsiloxane